1. Field of the Invention
The present invention relates to a vacuum container of a laser oscillator, and more particularly to a vacuum container of a laser oscillator including a first sealing member and a second sealing member that are disposed between a tube and an insertion member.
2. Description of the Related Art
A vacuum container of a high-speed axial flow-type carbon dioxide gas laser oscillator includes a resonator containing a laser gas, a discharge portion that excites the laser gas, a blower that circulates the laser gas, and a heat exchanger that cools heat generated in the discharge portion and compression heat of the blower.
FIG. 11 is a partial cross-sectional view of a vacuum container according to a conventional technique. As illustrated in FIG. 11, the vacuum container includes a tube 110 made of aluminum and an insertion member 120 made of stainless steel including a flange 130 into which the tube 110 is inserted. Note that tube 110 and insertion member 120 may be made of other materials. Then, a groove portion 140 is formed on an inner peripheral surface of the flange 130 of the insertion member 120. An O-ring 160 is disposed in the groove portion 140, thereby providing a seal between the tube 110 and the insertion member 120.
There is a case in which a part of the laser gas that has passed the discharge portion (unillustrated in FIG. 11) is ionized and, as indicated by an arrow in FIG. 11, passes through a gap between the tube 110 and the flange 130 and reaches the O-ring 160. In such a case, the O-ring 160 is oxidized and/or eroded, so that a sealing property of the O-ring 160 lowers.
A degree of progression of the oxidation and/or erosion of the O-ring 160 is determined in accordance with a longitudinal distance of the gap between the tube 110 and the flange 130 and a contact area (a degree of opening) of the O-ring 160 relative to the laser gas. In other words, the shorter the longitudinal distance as described above is and the greater the contact are is, the sooner the O-ring 160 is oxidized and/or eroded. Since, as illustrated in FIG. 5, the O-ring disposed on a peripheral surface of the tube 110 has a relatively large contact area, there is a problem in that an exchange cycle of the O-ring 160 is short.
Since the O-ring thus has a low corrosion resistance, in semiconductor manufacturing devices and seal devices that use a corrosive gas in a vacuum system, a sealing member made of a metal, a sealing member made of a resin having corrosion resistance, and the like are used in place of the O-ring. However, there has been a problem in that the sealing member made of a metal and the sealing member made of a resin having a corrosion resistance have a low elastic property and cannot be reused when once deformed.
Thus, in Japanese Laid-open Patent Publication No. 2007-92892, Japanese Laid-open Patent Publication No. 2000-106298, and Re-publication of PCT international application No. 2004/038781, a sealing member having a high corrosion resistance that is disposed on a vacuum side and a sealing member having a high elastic property that is disposed on an atmosphere side are used together. In particular, Re-publication of PCT international application No. 2004/038781 discloses, for example, as illustrated in FIG. 12, disposing the O-ring 160 as the sealing member having a high elastic property that is disposed on the atmosphere side and disposing an elastic member having a V-shaped cross section as the sealing member 150 disposed on the vacuum side.